Ortho-chelated arylrhodium(I) complexes. X-ray structure of RhI[C6H3(CH2NMe2) 2-o,o′-C,N ](COD)

Article abstract of DOI:10.1021/om00099a010

The reaction of Li_n[C₆H₃(CH₂NMe ₂)-o-R-o′]_n with [RhCl(diene)]₂ yields the ortho-chelated arylrhodium(I) complexes Rh[C₆H₃(CH₂NMe ₂)-o-R-o′](diene) (R = CH₂NMe₂, diene = COD (1a) or NBD (1b); diene = COD, R = Me (2) or H (3)). The solid-state structure of 1a was determined by a single-crystal X-ray diffraction study. C₂₀H₃₁N₂Rh: triclinic, space group P1, with lattice parameters a = 10.169 (1) ?, b = 13.036 (1) ?, c = 14.688 (2) ?, α = 79.54 (1)°, β = 77.04 (1)°, γ = 79.53°; V = 1845.6 (4) ?³, Z = 4; D(calcd) = 1.448 g cm^-3. Refinement with 4696 observed reflections converged at R = 0.0395. The structure of 1a consists of a rhodium(I) center that has a square-planar coordination comprising the two double bonds of COD and a C atom and one of the N atoms of the monoanionic aryl ligand. In solution compounds 1 and 2 exhibit dynamic behavior which involves a reversible dissociation of the Rh-N bond and rotation of the aryl moiety around Rh-C. This process, which generates a highly unsaturated T-shaped 14 electron species, is accompanied by the relief of steric repulsions within the complex. Complex 1 reacts with a range of electrophilic reagents leading to Rh-C bond breakage (HX, X = acac, Cl, Br, OAc, OH, OMe, L-alanyl; MX_nL_m, SnMe₂Br₂, NiBr₂(PBu₃)₂, ZrCl₄, PdCl₂(NCPh)₂, HgCl₂, PtBr₂(COD), and [IrCl(COD)]₂). A redox reaction of 1 with AgX (X = OAc, NO₃) leads to the formation of Rh^IIIX₂[C₆H₃(CH₂NMe ₂)₂-o,o′](H₂O).